Done the exact same thing only had the ladder on the bonnet of an old jaguar car. My boss nearly had a stroke lol
The best tip and it's a cliche don't look down if you're not comfortable with heights. Just concentrate on the job you're up there to do. We had a young lad on an open roof of a building he just couldn't get the nerve to step off onto to the ladder it was funny but after an hour had to go up and literally place his foot on the rung. He was like a f***ing cat coming down. Never went back on a height job again.
My closest to death was when i worked on the TSB office